Twins study: Anorexia risks determined at least halfway by genes

Also, link found between anorexia and childhood 'neuroticism.'

Also, link found between anorexia and childhood 'neuroticism.'

March 16, 2006

CHARLOTTE, N.C. (AP) -- Researchers studying anorexia in twins conclude that more than half a person's risk for developing the sometimes fatal eating disorder is determined by genes. Most experts already believe there is a strong genetic component to the disorder, which mostly affects girls and women. The new study "hammers home the fact that these are biologically based disorders," said Cynthia Bulik, lead author of the study who is a psychiatrist at the School of Medicine at the University of North Carolina-Chapel Hill. "We need to stop viewing them as a choice. ... The patients feel guilty, the providers tell them things like they should just eat, parents are blamed, the insurance companies won't fund treatment because they think it's a choice. It's held us back for decades." People with anorexia have a distorted body image and refuse to maintain a minimally acceptable body weight. Anorexia's rarity -- slightly more than 1 percent of females and well under 1 percent for males -- has made it hard for scientists to gather large groups of patients for study. The study by researchers at UNC and Sweden's Karolinska Institute looked at a Swedish registry of 31,406 twins -- both identical and fraternal -- born between 1935 and 1958. Identical twins are genetic clones, while fraternal twins are no more similar genetically than a brother and sister born in separate pregnancies. Anorexia was more prevalent between identicals, and statistical analysis led to the scientists' conclusion that 56 percent of the liability for developing anorexia is due to genetics, with environmental factors determining the rest, Bulik said. The study also found a link between anorexia and childhood "neuroticism," which Bulik describes as "a tendency to be depressed or anxious, and also to be emotionally reactive."